A Windows activation watermark appeared on a flight-information display above check-in signs at Heathrow Terminal 5, drawing attention to an apparent licensing or activation problem on the system running the screen. While it was unlikely to disrupt the display’s core function, the visible error could undermine passengers’ confidence in airport technology at the start of their journey.

The issue was spotted by a Register reader and published on 1 August 2026. Windows can show the watermark after hardware changes, updates or other activation-related problems; unactivated systems may retain security updates but face limitations and reduced support. The article notes Heathrow and British Airways’ previous IT and operational disruptions, though it does not establish that either organisation caused this specific issue.